What prepositions do
Prepositions never change their form and stand in front of a noun or pronoun. One Spanish preposition often covers two or three English ones, so learn each through the jobs it does, not as a single English word.
de - origin, possession, content
de says where something comes from (origin), who owns it (possession) and what it holds or is made of (content, material). Before el it becomes del: de + el = del.
Soy de Alemania.
I am from Germany.
Es el libro de María.
It is María's book.
Quiero una taza de café.
I would like a cup of coffee.
Vengo del mercado.
I am coming from the market.
a - direction, clock time, people
a marks the direction of a movement (to) and gives the time on the clock (at). As the personal a it also stands in front of a specific person used as a direct object; English has no counterpart and translates it with nothing. After tener it is dropped: Tengo una hermana. Before el it becomes al: a + el = al.
Voy a Madrid.
I am going to Madrid.
Comemos a las tres.
We eat at three o'clock.
Veo a María.
I see María.
Voy al cine.
I am going to the cinema.
en - place, time, transport
Where English chooses between in, on and at, Spanish uses one word: en covers a place, months and seasons, and the means of transport where English says by: en tren.
Vivo en Madrid.
I live in Madrid.
Mi móvil está en la mesa.
My phone is on the table.
Mi cumpleaños es en enero.
My birthday is in January.
Viajo en tren.
I travel by train.
con and sin - with and without
con (with) and sin (without) are a pair. With the pronouns mí and ti, con fuses into conmigo and contigo. After sin, a verb stays in the plain infinitive where English uses -ing: sin desayunar, without having breakfast.
Un café con leche, por favor.
A coffee with milk, please.
Un café sin azúcar, por favor.
A coffee without sugar, please.
Salgo sin desayunar.
I leave without having breakfast.
¿Vienes conmigo?
Are you coming with me?
Quiero hablar contigo.
I want to talk with you.
All together
Mi amiga es de México y vive en Madrid.
My friend is from Mexico and lives in Madrid.
Voy a la escuela con mi hermano.
I go to school with my brother.
Salgo de casa a las ocho y voy al trabajo en autobús.
I leave the house at eight and go to work by bus.
